All the cards you want to add I think would be great additions to the strategy but I have to ask... why Chainer, Dementia Master?!

Good point on not caring about targeted removal. Ignore the counterspells.

Lux Cannon seems out of place here with no proliferation.

Karn Liberated incredible card but does it fit this strategy? Liliana, Dreadhorde General has purpose.

By Invitation Only your enchantments and other removal spells will do the job better.

I was considering adding Chainer, Dementia Master to help steal other people's creatures after I killed all creatures on the board. Not a 100% sold on the idea but it would be interesting. I agree with Lux Cannon being out of place a little. I will cut it. Karn Liberated is included just for good removal or to potentially restart the game if I find myself in a really bad situation. I will cut By Invitation Only also. Next update is coming soon.

Stay true to the theme of all the creatures. If Plague Spitter doesn't fit than neither does Chainer. If you are looking to steal creatures maybe Ashen Powder, Beacon of Unrest or Gruesome Encore could fill the role without straying from the theme.

If Chainer caught your eye he is a really fun commander to build around Chainer, Dementia Nightmare Master

I decided to leave Chainer, Dementia Master out. I feel my newest additions are more for what the deck does or wants to do. I considered Beacon of Unrest but I don't think I want to cut anything for it. Perhaps Bontu's Monument?

Does Bontu's Monument grant the discount and/or the trigger when you return creatures from the graveyard with their activated abilities?

Not sure on that. I'm going to have to read about it.